Theory studies on the intermolecular interactions of urea nitrate with RDX

Six fully optimized geometries of urea nitrate cation and RDX complexes have been obtained with DFT-B3LYP and MP2 methods at the 6-311++G** level. The intermolecular interaction energies have been calculated with basis set superposition error (BSSE) and zero point energy (ZPE) correction. The nature of intermolecular interaction has been revealed by the analysis of AIM and NBO. The results indicate that the greatest binding energy of urea nitrate with RDX is -82.47kJ/mol. The O-H center dot center dot center dot O and N-H center dot center dot center dot Ohydrogen bonds are important intermolecular interactions of urea nitrate cation with RDX, and the origin of hydrogen bonds is the oxygen atom offering its lone-pair electrons to the sigma((O-H)*) or sigma((O-H)*). antibonding orbital. The intermolecular interactions strengthen the N-NO2 bond, leading to the reduced sensitivity of urea nitrate and RDX mixture explosive.